I was struck by Nassim Taleb's story in The Black Swan about the inventor of the laser. Far from having eyesight correction, compact disks, fibre optics, data storage or microsurgery in mind when he invented it, he was just satisfying his desire to split light beams. As Taleb observed "We build toys. Some toys change the world."
The moral of the story to me is simple: learn play! Rather than seeing education as the process of acquiring knowledge, we should see it as the first steps in learning to think. The knowledge we acquired may be dangerous, particularly as it displaces the unacquired knowledge that may turn out to be more useful in a particular real-life situation. Where it is useful it can often be acquired when needed, provided our education gave us the means to learn and to inquire.